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Flushing soil prior to harvest


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cross posted from  Basic simple growth medium question

Up date: Looking for clarification !!!

just the first indications of leave yellowing in the indicas. Now the 8 week finishers have received thier last feeding. ( but no milky capitate stalked glandular trichomes as of yet) and after drying out for 4-5 days will get a good flushing. and a good close view of the trichs.

we are looking at using the tips from  Franco's tricks.

 

I was looking for clarification on the pH adjustment for the flushing water for the medium mix  all the other info I think I have down Pat.

 

Franco states "Besides the normal watering cycle, it is also important to regularly flush the medium to get rid of salts. This can be done with a mild solution at pH 5.5 and EC 1.0, so that the salt crystals can bind to the low-mineral-content in the solution and dissolve. Flushing should be integrated in the regular watering cycle, and after flushing the medium should be allowed to dry properly before feeding again."

 

I assume this holds for preharvest finishing as well however no clarification as far as pH is concerned is made between hydro and soil. Does the 5.5 PH recommendation hold for soil as well?

72 degree F Water Temp

looking for 20%+ effluent with a similar EC and pH as input

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soil PH should be kept at around 6.5  the same is with hydro.. theres lots of conflicting data out there.. and what i see a LOT is when people have the PH lower than 5.8 they tend to start to see cal-mag def, so they ad cal-mag to fix it.. calcium precipitates out of the solution at 6.2ph.. i aim for a ph of around 6.3 (5.8-6.8 being the range) 6.3 comes in the middle ..

when growing in soil, flushing is less important as you dont seem to pump as much fertilizers into the medium as you do with hydroponics, most growers tend to stop the flower ferts and just use water for the last few weeks, this alone helps flush the medium of any unwanted salts and also helps flush the plant aswel.

hydroponics on the other hand is a little different, with the constant nutrient circulating youll get a salt build up. Depending on what type of medium, depends on how much gets built up.

ive heard of a few people flushing with a mild nutrient solution and really its a waste of time, and nutrients. I use just plain water when flushing, i dont bother to adjust the ph.. some do.. but its not really necessary as youre only flushing the medium. Once its done its back onto nutrients, then you adjust the ph..

either way works tho, so choose what you think suits

as far as i am concerned about PH, theres NO diference between soil and hydroponics on the plants side of things.. with extensive research into this all i have found is you keep a soil ph of 6.5 to keep the microbial bacteria in the soil happy. as for the plant i was told some 25 or so years ago.. 6.3 is where the root zone needs to be to get the correct balance of nutrients. Altho as stated before the range is between 5.8 and 6.8 you aim at 6.3 to try and find middle ground, if its slightly higher or lower it shouldnt matter a real lot, also allows for slight fluxuations.

what ive found is a lot of people these days tend to supplement thier solution with cal-mag.. i find this is becuase the PH is set too low, as stated cal precipitates out of the solution at 6.2PH so at 5.5.. ofc youll need to ad cal-mag altho i cant see it helping a real lot if the PH is too low for the plant to use it..

lastly.. in the 25+ years ive been growing indoors ive NEVER had to use cal-mag to supplement my nutrients.. if you use a proper all round hydroponic nutrient you shouldnt have to use it..

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soil PH should be kept at around 6.5  the same is with hydro.. theres lots of conflicting data out there.. and what i see a LOT is when people have the PH lower than 5.8 they tend to start to see cal-mag def, so they ad cal-mag to fix it.. calcium precipitates out of the solution at 6.2ph.. i aim for a ph of around 6.3 (5.8-6.8 being the range) 6.3 comes in the middle ..

when growing in soil, flushing is less important as you dont seem to pump as much fertilizers into the medium as you do with hydroponics, most growers tend to stop the flower ferts and just use water for the last few weeks, this alone helps flush the medium of any unwanted salts and also helps flush the plant aswel.

hydroponics on the other hand is a little different, with the constant nutrient circulating youll get a salt build up. Depending on what type of medium, depends on how much gets built up.

ive heard of a few people flushing with a mild nutrient solution and really its a waste of time, and nutrients. I use just plain water when flushing, i dont bother to adjust the ph.. some do.. but its not really necessary as youre only flushing the medium. Once its done its back onto nutrients, then you adjust the ph..

either way works tho, so choose what you think suits

as far as i am concerned about PH, theres NO diference between soil and hydroponics on the plants side of things.. with extensive research into this all i have found is you keep a soil ph of 6.5 to keep the microbial bacteria in the soil happy. as for the plant i was told some 25 or so years ago.. 6.3 is where the root zone needs to be to get the correct balance of nutrients. Altho as stated before the range is between 5.8 and 6.8 you aim at 6.3 to try and find middle ground, if its slightly higher or lower it shouldnt matter a real lot, also allows for slight fluxuations.

what ive found is a lot of people these days tend to supplement thier solution with cal-mag.. i find this is becuase the PH is set too low, as stated cal precipitates out of the solution at 6.2PH so at 5.5.. ofc youll need to ad cal-mag altho i cant see it helping a real lot if the PH is too low for the plant to use it..

lastly.. in the 25+ years ive been growing indoors ive NEVER had to use cal-mag to supplement my nutrients.. if you use a proper all round hydroponic nutrient you shouldnt have to use it..

 

yeah but you still have the calcium and magnesium in the tap water as do most places with bad water quality so the comparison doesnt apply to a place with good drinkable tap water i see this claim made up daily by people with lots of cal in there tap... for example my tap has 20ppm cal and pf has 0 so its pretty clear calcium supplement is must with that hydroponic nutrient      its  apples and oranges comparison when you talk about YOUR tap water

 

your tap is not ghosts tap or my tap this has been talked thru in chat many times and everytime you think the water is same all around globe for every one and they all got enough cal... well they dont

 

i would not make huge generalizations of things that cannot be generalized  like feeding, ph or salt build up in soil

 

there is clearly huge difference on the ph ranges with soil and hydro it is obivous and they are clearly different. what you think doesnt change evidence unless you some kind of evidence, but i do agree on the range you say for the most part and that people usually get the cal mg issues from too low ph and the low ph usually comes from over using nutrients

 

also every variety doesnt like same ph range dooh so the generalization is useless yet again(some people seem to think all cannabis is same and from same soil:D) 

indica from mountain and sativa from tropical island dont have same optimal ph ranges, the native soils where cannabis evolved had different ph's so different land races have adapted to new ph ranges... this is all common knowledge there is no single ph value for the different grow stages either so making generalizations in ph is totally unnecessary and pointless

 

if you grow organically i would follow ph ranges where fungi and bacteria are most happy as they are doing the work.   6.3 would be the very very lowest ph in this case and not the optimal. 6.3-7.0 or around there for liliving soil with organic nutes like you have

and with synthetics  i would feed with 6.3 or approx, if its hydroponic with synthetic than even lower  (soil with hydro nutes or coco with hydronutes or pure hydro with hydro nutes makes different ph range for plant as nutrient availability changes in the mediums aswell)

soil with organic is not same ph range as soil with synthetic and soil with synthetic is not same as dwc ph range, the material/medium changes it or lack of it and there is mountain of evidence for it skunk

 

you can add ph8 water in healthy soil and it will buffer the water ph down to propriate level in mere minutes but if you put in water in bucket, nothing no buffering that is pretty huge difference right there. 

there is no way to generalize them in same number in any way its like comparing apples and oranges again and saying they taste exactly the same

 

''Does the 5.5 PH recommendation hold for soil as well?''   no it doesnt you can add very high ph water and soil can buffer it to the range very easy but soil is not so good at buffering acidic water up only down

 

you preloaded the soil with all kinds of organic nutes but you also said you fed it last time too? so are you feeding synthetics or organics on top?  flushing doesnt work the same on the organic nutrients

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Ive seen way too much lime induced chlorosis out here with our heavily mineral salted water ( 8.1 pH w/ 1Kpph+ ) to ever want to run tap over anything living. Ok maybe the out side of dog but thats about it.  Ive seen well meaning gardeners absolutely  poison rich expensive organic mediums not to mention plantings with our tap water.

Tap is simply out of the question. a adjusted pH buffered solution of low particulate and mineral content (r/o) just makes sense.

Soil pH as tested electronically with water soluble testing instruments and reveled mid 6 pH levels of the soil I was assuming that I would get this or a similar pH effluent. 7.3 seemed high but no where near where toxicity levels or lock up may be an issue

 

My mind has me using 100% organic based feedings in an effort to assure immediate bio-availability during crucial points in the life cycle. (utilizing teas and home brewed solutions) However the owner wanted to use a commercially available organic based water soluble nutrient regimen due to ease of use and exactitude. I was down with this primarily because we would want to ensure immediate bio-availability of those nutrients crucial to the floral production during that time. And I felt levels weren't going to be an issue with the owner because of his tendency to under fert as a practice.

 

yes I under stand that bio solids in various stages of decomposition are not readily flushed from the substrate in this manner.  And for the buffering effect of soils with high levels of humus and biological activity (thank Jah for little (or big) miracles.)

 

Never the less this did not persuade me not to pursue a vigorous flushing regimen due to the store bought juice ( Im glad we did because of the resultant pH of the effluent and, not incidentally to me, the smell of it. )Personally I like to give this form of  vegetation Herbs edible flowers ect.  a good flushing prior to harvesting. (if you have ever drank cat nip tea where the nip was fertilized with lawn fertilizer you'll  know why: p )

I will take to heart your recommendations on the pH of the solution and leave it up there around 6.5 thank you for them.

 

this may be a more understandable resource for LIC 

  http://pep.wsu.edu/hortsense/scripts/query/displayProblem.asp?tableName=plant&problemID=311&categoryID=1

or

https://archive.org/stream/treatmentoflimei321benn/treatmentoflimei321benn_djvu.txt

a workable fix

http://www.abc.net.au/gardening/stories/s717845.htm

as an aside here a wonderful resource for many plant ailments or pest issues for your perusal

enjoy...

http://www.crocus.co.uk/features/_/pests-&-diseases/lime-induced-chlorosis/articleid.1043/

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